This invention relates to the preparation of gamma-butyrolactones and their use as cross-linking agents in various processes, including coating applications. Gamma-butyrolactones as cross-linking agents impart favorable properties to coating materials, do not pose serious health risks in commonly used coating processes, and therefore are suitable alternatives for isocyanates in coating compositions and application processes.
Materials commonly used for coatings, particularly those used in the automotive industry, utilize isocyanate compounds in coating formulations due to cross-linking properties of the compounds. Diisocyanate compounds react slowly at room temperature with amines and aliphatic alcohols to make polymers having urethane or urea crosslinks. Isocyanates may also cross-link with amines or alcohols during a baking step of the coating process and result in urethane or urea crosslinked polymers. Both urethanes and ureas are known to impart desirable properties in coating materials. Polymer backbones appended with hydroxyl groups or amine groups harden coating materials such as paint.
Isocyanates are volatile compounds. During the coating or baking step, persons working in the automotive industry, for example, are exposed to the vapors. Concern about the potential toxicity and health related effects associated with isocyanates suggests that alternatives are needed. The present invention discloses alternatives to isocyanates as cross-linking agents.
Disclosed in this invention is a lactone composition, as represented in structure I, wherein each n is independently 1 to 3; L is either present as a substituent having two functional groups, or is a direct bond forming a spiro-butyrolactone, or is H wherein rings of the structure are not connected, or is a radically polymerizable group wherein the rings of the structure are not connected; Y is either present independently as alkyl, alkenyl, alkynyl, aryl or a direct bond; each X is independently a substituent having a field effect, F, between xe2x88x920.42 and +1.58
Also disclosed in this invention is a process comprising contacting lactones of structure B with an amine to form a hydroxy amide, wherein each Y is present independently as alkyl, alkenyl, alkynyl, aryl, or a direct bond; each X is independently a substituent having a field effect, F, between xe2x88x920.42 and +1.58; wherein R is a branched or straight chain alkyl group of C1 to C10, or an aryl group; and wherein each n is independently 1 to 3. 
This invention also discloses a process comprising contacting a spiro-bislactone of structure A, wherein each n=1 to 3 independently and R is a branched or straight chain alkyl group of C1 to C10, or an aryl group; with an amine to form a hydroxy amide. 
Also disclosed in a process comprising contacting a bicyclo-lactone of structure C wherein R is a branched or straight chain alkyl group of C1 to C10, an aryl group; or C(O)OE wherein E is independently alkyl or aryl, with an amine. 
Also disclosed in this invention is a process comprising contacting a polymer comprising at least one polymerized lactone monomer of structure D with an amine to form a hydroxy amide, wherein each Y is present independently as alkyl, alkenyl, alkynyl, aryl, or a direct bond; each X is independently a substituent having a field effect, F, between xe2x88x920.42 and +1.58; and wherein RPG is a radically polymerizable substituent group selected from the group consisting of styrene, acrylate, methacrylate, acrylamide, and methacrylamide; and wherein n is independently 1 to 3. 
Still another disclosure of this invention is a process, comprising:
(i) performing the steps of any one of the disclosed processes; and applying a product resulting from step (i) to an object surface.
Also disclosed is an article treated by a process disclosed as described above.